Kuroi Kitsune
by Grilled Cheesby
Summary: Sasuke defeats and kills Naruto at the Valley of the End and it's only afterwards he realizes that he never wanted the blonde dead. Panicking, he tries to use medical chakra to revive Naruto, only Sasuke doesn't know what he's doing. His desperation causes his Sharingan to do something unprecedented when mixed with the leaking Kyuubi chakra coming from Naruto. Full summary inside.


**Story Summary:** _Sasuke defeats and kills Naruto at the Valley of the End and it's only afterwards he realizes that he never wanted the blonde dead. Panicking, he tries to use medical chakra to revive Naruto, only Sasuke doesn't know what he's doing. His desperation causes his Sharingan to do something unprecedented when mixed with the leaking Kyuubi chakra coming from Naruto: Naruto is brought back to life and Sasuke is suddenly a small, black fox. Canon AU starting after their first Valley of the End fight. NaruSasu/SasuNaru_

 **Chapter Summary:** _Sasuke looks at his rival and closest friend's face and tries to steel himself. He needs to kill Naruto to get stronger and staring at the knocked-out blonde won't get him anywhere. He shifts, ready to grab one last kunai to get this over with when he notices that the blonde isn't breathing._

 _Sasuke's heart stops._

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 **Chapter 1:** _Consequences_

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Sasuke's life has revolved around vengeance for longer than he's been alive. He's made every decision and every action he's ever done based around his need to kill Itachi and avenge his clan. Sasuke's only defied his own ambitions once in his entire life and it was because he couldn't let Naruto die at Haku's hands. He refuses to look to deeply into it, tells Naruto and himself that he moved without thinking. That he hadn't made the choice to save Naruto at the cost of his life and future.

It's this thought that runs through his head as rain soaks into his clothes, his head bowed over Naruto's own. His injuries are painful, his shoulder in particular causing pain throughout his arm. Naruto's eyes are closed and his usually bright blonde hair is darker from the torrential downpour. Sasuke looks at his rival and closest friend's face and tries to steel himself. He needs to kill Naruto to get stronger and staring at the knocked-out blonde won't get him anywhere. He shifts, ready to grab one last kunai to get this over with when he notices that the blonde isn't breathing.

Sasuke's heart stops.

Naruto isn't breathing, which means he's dead. Sasuke has already succeeded. He's finally killed Naruto.

 _He killed Naruto._

Sasuke scrambles forward with weak arms and aching legs, moving to Naruto's side to put his ear against his chest. He listens for a heartbeat, prays for one, but he can't hear one and the rain is drowning out everything. If Naruto has a faint heartbeat, Sasuke can't hear it and it won't be for long. He checks his pulse next and his suspicions are confirmed when he only feels wet clammy skin and no pulse.

Sasuke immediately starts chest compressions. His entire body is weak with exhaustion and he's growing colder the longer he's in the rain, but he's nowhere near as cold as Naruto is because he's not _dead_.

He's not laying on the ground, body with no soul, as the boy who killed him worked desperately to erase his actions. Sasuke let's out a broken sob, not even caring about his loss of composure as he pinches Naruto's nose closed and leans forward, shakily breathing into Naruto's mouth.

Their lips touch, but it's not disgusting as much as it is desperate. Sasuke's delirious mind flashes back to that moment in the academy, just before team assignments, when they shared an accidental kiss. It had been painful and in now way elegant, and yet Sasuke finds this to be so much more painful.

He's shaking as he lets up, continuing with chest compressions and then following the cycle once again, trying to breathe air into the lifeless body below him. He does it again and again and yet nothing happens, _it doesn't work_ , and Sasuke is becoming even more desperate. He's exhausted, close to collapsing, but he can't stop. He can't walk away or stop his hands from pushing against Naruto's chest.

He can't let Naruto die. Sasuke's eyes burn as he cries above his dead friend, his actions becoming more and more desperate. His vision is swimming now, and not just because of the rain. He can feel his already reduced chakra reserves dwindling and he finally notices the sticky feeling of blood sliding down his face.

He shakily wipes the blood away, smearing it across his cheeks, and hesitantly brings his hand in front of his face. He's crying tears of blood. A memory ignites in his head and Sasuke sobs again, more blood and tears falling. He's managed to do it. He killed his closest friend and he's achieved the higher form of the Sharingan: the Mangekyou Sharingan.

 _Not worth it_ , he thinks, _it's not worth it._

He collapses against Naruto's side, his head resting on Naruto's still chest and he closes his eyes, the chakra being syphoned to his eyes suddenly cutting off and leaving him even weaker. He's pathetic he knows. This is what Sasuke wanted, Naruto dead and his eyes evolved, and yet here he is, realizing too late that none of this was what he ever truly wanted. Sasuke wanted to not be alone. He wanted to finally have something to live for. Now, all he has to look forward to is death.

A wisp of chakra flares from his curse seal and Sasuke jolts, his eyes opening and his Mangekyou Sharingan spinning. He doesn't have much chakra left. The seal has just a bit more, but still not a lot either. He's never performed medical ninjutsu before, only read about the basics one night many years ago because he was bored.

 _But_ , Sasuke acknowledges, _he's beyond desperate._

His eyes spin as he puts his hand on Naruto's chest, pushing himself to grasp any remaining chakra and then focusing it in his hands. His eyes are straining, still activated as he stares down at his friend. The curse seal on his neck is burning suddenly, fighting the desperate pull Sasuke is attempting. Sasuke doesn't even hesitate as he rips at the seal's stored chakra, tugging it out and into his now burnt chakra coils. If Sasuke survives this, which he sincerely doubts, he will more than likely never be able to perform ninjutsu again.

He doesn't care.

His eyes are now giving him a migraine, a sharp pain ringing throughout his head, but he doesn't stop pushing chakra. His hands aren't glowing green, not like he's seen when medically trained shinobi do it, but he doesn't even hesitate as he places his hands on Naruto's chest and _pushes_. Naruto's chakra reserves are a cavern and they drain Sasuke's meager reserves within seconds.

He doesn't stop scraping at himself, though. He has almost no chakra left to give. He doesn't hesitate to give his life. His eyes burn one last time as he gives and gives and gives and _refuses_ to let the reality before him continue to exist.

There's a sudden pull, his eyes not deactivating like they should be. Instead of funneling chakra into Naruto, he's taking chakra out. Sasuke is confused and he starts to panic, not sure what's happening. He's pushing towards Naruto and yet his eye continues to pull chakra out, spinning faster and faster as it draws chakra into it. The chakra that is being pulled suddenly turns purple and then red and Sasuke's body burns with acid as his eye suddenly comes into contact with the Kyuubi no Kitsune's volatile chakra. His eyes doesn't stop straining though, he notices hysterically, just continues to take what isn't his.

He's kept his hand against Naruto's chest during his freak out, but he abruptly pulls away, cutting off the connection in a desperate attempt to stop whatever is happening. Several things happen simultaneously.

His Sharingan stops syphoning chakra and instead activates something that Sasuke has never used before. The air shifts around them, heavy and filled with something that Sasuke can't begin to understand. The amassed chakra swirls and shifts and Sasuke watches as reality itself moves backwards because Naruto is suddenly _breathing_.

It's so very faint, and it could just as easily stop again, but Sasuke can finally see his chest moving up and down. His eyes deactivate on their own and Sasuke can feel a tingling sensation hovering over his body. His eyes are growing dark in his periphery and he knows he's going to pass out soon. This could very well be the last time Sasuke thinks anything. He doesn't even mind that's he's dying because Naruto is _alive_.

A cool, watery film covers Sasuke's senses as he collapses to the ground, quickly losing the ability to stay up and functioning. He can feel his limbs curl up against his torso and then a strange burn comes through him, similar to the feeling the Kyuubi chakra had caused in his eyes.

Sasuke loses consciousness before he can give it anymore thought.

Sasuke is abruptly forced into consciousness when he senses Kakashi's worried chakra standing nearby.

He forces his eyes open, his lids heavy, and he is suddenly looking at a sad and worried Kakashi as he bends down to pick up an unconscious Naruto. Sasuke clocks onto the fact that Naruto is still breathing and he lets out a relieved breath.

Sasuke's vision is weird, the color saturation off, but he can't make himself be overly concerned with it. His eyes did something to help him bring back Naruto, so he wouldn't be surprised if he's damaged them beyond repair. He doesn't even care that his family dojutsu may now be out of his reach.

Naruto is alive and that's all that matters.

He tries to sit up and is disconcerted when his vision isn't the only thing that's weird. His body is cooperating, as he shifts, but his muscles feel odd and his center of balance is way off. He turns and he knows that he suddenly weighs far less than he ever remember weighing. He finally looks down and paws are what he focuses on.

 _Paws_.

What the hell did he do?

"Naruto," Kakashi's shaking voice brings him out of his panic and he forces himself to look up, up, up, at his sensei. Kakashi is gripping Naruto in his arms, staring sadly down at him. Sasuke is suddenly aware of the other presence in their vicinity and he looks over at Pakkun who looks just as devastated as his master does.

Kakashi looks off in the direction of Sound, something that makes Sasuke think his sensei is thinking of him, before he turns and starts to make his way out of the Valley of the End.

Sasuke start to panic because Kakashi hadn't noticed him and he doesn't know what to do. Sasuke brought Naruto back, but it obviously had some unseen side effects because Sasuke now has four legs and paws. He doesn't know what he is yet, but he can feel his thick fur matted down against his skin and the trembling tail tucked between his legs. He pushed himself up, forces himself to stumble after Kakashi, and he shouts, "Wait!"

His plea comes out as a barking scream and Sasuke absentmindedly crosses off felines as a possible candidate for his new form.

Kakashi does stop at his cry, turning around in confusion. He finally spots Sasuke's soaked form and as depressed as he's obviously feeling, he still brings himself to raise an eyebrow.

"A black fox?" Kakashi asks himself in confusion.

 _That answers that question,_ Sasuke thinks with a huff, stopping in front of Kakashi and looking up at him.

Kakashi stares back for a moment, his gaze bewildered, before he physically shakes himself, dismissing Sasuke. "I don't have time for this. Naruto needs medical attention."

Sasuke panics, watching Kakashi turn away, and he lets instinct overcome him. One second he's on the ground, back legs bunching up in anticipation, and the next he's jumping up, latching his teeth onto Kakashi's arm.

The jounin curses, truly caught by surprise, and he glares at Sasuke's dangling form. Sasuke doesn't let up, his jaw tense. Kakashi eventually huffs in frustration, rolling his visible eye, before continuing his cold glare. "Fine, you can come, but don't get in my way."

Sasuke uses his front paws to drag himself up and suddenly he's pressed against Kakashi's chest, resting on Naruto's stomach. Kakashi springs forward, heading towards Konoha with Pakkun following soon after. Sasuke pays no mind to either of them, nor to their journey, but instead clumsily makes his way up from Naruto's stomach to his chest. He tucks his head against Naruto's own lulling head and he curls up carefully. They're all soaking wet, making him feel wet and miserable, but he pays it no mind as he shares his miniscule warmth with his blond teammate.

Sasuke is more than confused by the events that have just taken place, but he regrets nothing as Naruto's chest rises below him and his soft breaths run warm against Sasuke's soggy fur.

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 **this rabies infested nonsense bit me and i couldnt shake it. this fic has annoyed me for four god damn years. ive had to do research into the naruto canon verse to write _the jikan phenomenon_ so i said fuck it and wrote this motherfucker**

 **enjoy**


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